I. Field of the Invention
This invention relates generally to wireless communication systems. More specifically, the invention relates to call processing in a wireless communication system.
II. Description of the Related Art
Wireless systems are becoming a fundamental mode of telecommunication in modern society. As wireless systems continue to penetrate deeper into the telecommunications market, the demand for user features will only continue to increase. Special user features allow individual carriers to distinguish their services over other wireless carriers. As such, the user features continue to be an important part of a wireless communication system.
FIG. 1 is a block diagram showing a typical modern wireless communication system 10. The system is comprised of a series of base stations 14. A set of remote units 12 communicate with the base stations 14. The remote units 12 communicate with the base stations 14 over a forward link channel 18 and a reverse link channel 20. FIG. 1 shows a variety of types of remote units. For example, FIG. 1 shows a hand-held portable telephone, a vehicle mounted mobile telephone and a fixed location wireless local loop telephone. Such systems offer voice and data services. Other modern communication systems operate over wireless satellite links rather then through terrestrial base stations.
When a subscriber wishes to place a call, typically he enters a telephone number into the keypad of his remote unit 12. A message is sent over the reverse link channel 20 to the base station 14 and a bi-directional communication channel is established between the base station 14 and the remote unit 12. In a similar manner, when a call arrives at the base station 14 for the remote unit 12, the base station 14 sends a message to the remote unit 12 over the forward link channel 18. The remote unit 12 responds to the message and bi-directional communication is established between the remote unit 12 and the base station 14.
In some instances, it is advantageous to provide additional information to the subscriber upon call origination or call receipt at the remote unit 12. In addition, some types of calls should be handled differently by the system 10 than others.
Some prior art systems allow the subscriber to enter phone book entries into the remote unit. Using the phone book entries, the subscriber can identify commonly used telephone numbers and designate them with a corresponding text entry. For example, if a salesman places several calls a day to his home base, he makes a phone book entry which designates his home base. When he wishes to call home base, he enters a telephone number or a set of shortcut keystrokes in order to place a call to the home base. The telephone number is compared with the phone book. The phone book comprises a subscriber-designated text field corresponding to information that will be displayed during the call connection. Typically a liquid crystal display (LCD) shows the text “HOME BASE.” Likewise, when an incoming call is received, if caller identification is available, the calling number is compared to the phone book entries. If a corresponding phone book entry is found, the display shows the corresponding text entry. For example, if a regular customer of the salesman calls, the display shows the subscriber designated text “BOB'S FISH EMPORIUM.”
These subscriber designated text messages are each associated with standard voice or data telephone connections. In some instances, the subscriber places or receives a special, nonstandard connection. For example, the subscriber can place an emergency call which triggers special call processing procedures. These specials calls are often associated with an industry standard phone number such as 911. However, these standard phone numbers are not universally accepted and can vary from country to country. The carrier needs to remain in control of the calls which are designated as emergency calls because the special call procedures associated with emergency calls consume more resources than standard calls. For this reason, it is not practical to allow the subscriber to designate certain phone numbers to correspond to nonstandard connections. In addition, the infrastructure equipment is typically designed to reject connections which are designated as emergency calls unless the phone number corresponds to a known emergency phone number. Thus, if the subscriber attempts to enter his own emergency number, the remote unit may enter an inconsistent state when the designated number is dialed. Because the phone numbers which trigger these nonstandard connections can be customized locally, it is not practical to hard code these numbers into the remote units.
Therefore, there is a need in the industry to develop a special means of call processing for nonstandard connections.